Blue cotton dye



v UNITED STATES PATENT OFFICE.

ROBERT DEMUTH, OF ELBERFELD, GERMANY, ASSIGNOR TO THE FARBEN- FABRIKEN OF ELBERFELD COMPANY, OF NElV YORK.

SPECIFICATION forming part of Letters Patent No. 620,428, dated February 28, 1899.

Application filed July 26, 1898. $erial No. 686,963. (N0v specimens.)

T0 ctZZ whom it may concern:

Be it known that 1, ROBERT DEMUTH, doctor of philosophy and chemist, of Elberfeld, Germany, (assignor to the FARBENFABRIKEN on ELBERFELD COMPANY, of New York,) have invented a new and useful Improvement in the Manufacture of Blue Cotton Dyes; and I do hereby declare the following to be an exact and clear description thereof.

My invention relates to the production of blue cotton dye by subjecting 1.8 chloronaphtliolsulfo-acids to the action of alkaline sulfids and sulfur at elevated temperatures and subsequently treating the resulting melt in a suitable manner in order to isolate therefrom the blue dye, which isolation may be effected by repeatedly treating the melt with small quantities of hot water, filtering off the solutions thus formed, continuing this extraction until the blue dye contained in the melt has been wholly dissolved out, and finally precipitating from the resulting filtrates the blue dye with common salt, zinc chlorid, zinc ammonium chlorid, or the like. In case zinc chlorid is used the precipitates when filtered off, pressed, dried, and pulverized are blackish powders insoluble in water, in sodiumcarbonate solution, and in hydrochloric acid, (21 Baum,) for the most part soluble in soda-lye (40 Baum) with a bluish color, in

. concentrated sulfuric acid (66 Baum) with a dull bluish-red color, and in hot watery solutions of sodium sulfid with a brownish color, which turns into blue at exposure to the air. The products thus obtained dye unmordanted cotton in alkaline baths blue shades which are fast against the action of alkalies and light and-yield the same shades whenthey are dyed in hot or cold baths containing suitable reducing agents. -0n using hot baths alkaline sulfid or alkaline carbonate and grape-sugar may be profitably employed as reducing agents, while in the case of using cold baths alkaline sulfid is used with preference.

In order to carry out my process practically, I can proceed as follows without limiting myself to the details given, the parts being by weight: Fifty parts of 1. 8-chloronaphthol-2A- disulfonate of sodium are stirred into twenty parts of soda-lye (40 Baum) and eighty-one parts of dry sodium sulfid, and seventy-five mass is well stirred and keeping the same at l the said temperature until it has become solid and can be easily minced to form a powdery mass. At thisstage the vessel is closed, the temperature of the bath is raised to 240 centigrade, and heating is continued for about four hours. After cooling the blackish powdery melt is taken out from the vessel and repeatedly treated with small quantities of hot water, the resultingsolutions are poured on a filter, and this extraction of the melt is continued until the blue dye is wholly dissolved out. From the joint filtrates the blue dye is precipitated by means of a solution in water-of-zinc chlorid. When filtered ofi, pressed, dried, and powdered, it forms a blackish powder insoluble in water, sodiumcarbonate solution, and hydrochloric acid of 21 Baum, for the most part soluble in sodalye (40 Baum) with a bluish color, in concentrated sulfuric acid (66 Baum) with a dull bluish-red color, and in hot watery solutions of sodium sulfid with a brownish color, turning into blue at exposure to the air. It dyes unmordanted cotton in alkaline baths blue shades which are fast against the action of alkalies and light and yields the same shades when it is dyed in boilin'gbaths containing sodium sulfid or sodium carbonate and grape-sugar or when it is dyed in cold baths containing sodium sulfid or the like.

The process proceeds in an analogous manner if in place of sulfur and sodium sulfid used in the aboveexample other mixtures or compounds containing alkaline sulfid-such as sulfur and potassium sulfid, sulfur and soda, sulfur and potassa, sodium polysulfid, potassiumpolysulfid, or the likeare employed. The-same result is obtained if the 1.8-chloronaphtho1-2. l-disulfo-acid used in the preceding example is replaced by other 1.8-chloronaphtholdi or monosulfo-acids.

Having now described my invention and in what manner the same is to be performed, what I claim as new, and desire to secure by Letters Patent, is-

1. The process for the production of blue cotton dyes, which process consists in subjecting sulfo-acids of 1.8 chloronaphthol to the action of an alkaline sulfid and sulfur at elevated temperatures, repeatedly extracting the resulting melt when cold with small quantities of hot water, until the blue dye is wholly dissolved out, and finally isolating from the joint filtrates the dye by precipitation with chlorid of zinc, for which a similar metallic salt may be used, substantially as hereinbefore described.

2. The process for the production of a blue cotton dye, which process consists in subject-- ing 1.8 chloronaphthol 2.4 disulfo-acid to'the action of an alkaline sulfid and sulfur at elevated temperatures, repeatedly extracting the resulting melt when cold with small quantities of hot water, until the blue dye is wholly dissolved out, and finally isolating from the joint filtrates the dye by precipitation with zinc chlorid, substantially as described.

3. As a new article of manufacture the blue dyes obtainable from sulfo-acids of 1.8 chloronaphthol, forming when precipitated by means of zinc chlorid, dried and pulverized, a blackish powder, insoluble in water, sodiumcarbonate solution and hydrochloric acid (21 Baum), for the most part soluble in sodalye Baum) with a bluish color, in concentrated sulfuric acid (66 Baum) with a dull bluish color, and in hot watery solutions of sodium'sulfid with a brownish color turning into blue at exposure. to the air, producing on unmordanted cotton in alkaline baths and in baths containing suitable reducing agents blue shades fast to the action of alkalies and light, substantially as hereinbefore described.

4. As a new article of manufacture the specific blue dye obtainable from 1.8 chloronaphthol 2.4 disulfo-acid, forming when precipitated by means of zinc chlorid, dried and pulverized, a blackish powder, insoluble in water, sodium-carbonate solution and hydrochloric acid (21 Baum), for the most part soluble in soda-lye (40 Baum) with a bluishcolor, in concentrated sulfuric acid (66 Baum) with a dull bluish-red color, and in hot watery solutions of sodium sulfid with a brownish color turning into blue at exposure to the air, producing on unmordanted cotton in alkaline baths and in baths containing suitable reducing agents blue shades fast to the action of alkalies and light, substantially as described.

In testimony whereof I have signed my name in the presence of two subscribing witnesses.

ROBERT DEMUTH.

Witnesses:

R. E. JAHN, Or'ro Komc. 

